Clinical treatment of infants in the neonatal intensive care unit (NICU) is particularly challenging due to their small anatomies, medical instability, and immature physiological processes. Treatment is often complicated by the lack of therapeutic devices and instrumentation designed specifically to accommodate this unique patient population. For instance, current vascular access catheters are not specifically designed and customized for the very small vasculature of neonatal patients, which exacerbates common complications including vessel perforation, thrombotic occlusions, catheter breakage, and infection. Creating sophisticated, patient-specific neonatal catheters would dramatically reduce these complications and work to better serve this population. 3D printing offers the ability to generate complex and patient-specific 3D architectures. Our collaborators at Northeastern University are pioneering 3D Magnetic Printing, a new technique in which reinforcing ceramic fibers are aligned with magnetic fields during the printing process to create composites with highly tunable reinforcement architectures. We will use 3D Magnetic Printing to produce strong, flexible, patient-specific neonatal vascular access catheters. Specifically, we will generate customizable composite catheter tubing with enhanced wall stiffness and strength while maintaining flexibility, burst strength and kink resistance. Such a novel design approach will allow production of next generation neonatal vascular access catheters with thinner walls, permitting reduction of catheter diameters and/or higher fluid transport rates. 3D Magnetic Printing of neonatal catheters offers the advantages of improved resistance to catheter sidewall collapse and kinking that often leads to catheter occlusion, and higher fluid transport rates which will minimize the probability of thrombus and fibrin sheath formation. Furthermore, the 3D printing technique is compatible with conventional catheter materials such as polyurethane and silicone and allows utilization of biocompatible fibers like hydroxyapatite facilitating regulatory approval pathways. The printing method is robust, low cost, and scalable. In Phase I we will print a variety of catheter tubing with customized fiber architectures including longitudinal, lateral, and radial reinforcement using both polyurethane and silicone. Sample characterization will be used to fine tune a finite element analysis model of the material. This model will be used to design improved tubing for comparison to conventionally extruded tubing. Our primary objective is to demonstrate the production of tubing with reduced wall thickness, optimized mechanical properties, and enhanced flow characteristics. In Phase II this model will be used to design functional catheters having complex reinforcement architecture.